ANS observations of Cygnus X-1 |
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| Authors: | D R Parsignault A Epstein J Grindlay E Schreier H Schnopper H Gursky Y Tanaka A C Brinkman J Heise J Schrijver R Mewe E Gronenschild A den Boggende |
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| Institution: | (1) American Science and Engineering, Inc., Cambridge, Massachusetts, USA;(2) Center for Astrophysics, Harvard College Observatory and Smithsonian Astrophysical Observatory, Cambridge, Massachusetts, USA;(3) Space Research Laboratory, Utrecht, Netherlands |
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| Abstract: | Cygnus X-1 was observed from 3 November until 9 November, 1974, using the hard X-ray (1–28 keV) and soft X-ray (1–8 keV) experiment on board the Astronomical Netherlands Satellite. On three occasions, on 4 and 5 November, the X-ray spectrum was observed to be harder, while the flux intensity in the 1–7 keV ranges decreased by  50% from its quiescent value. These events occurred near and following the time of superior conjunction of the likely optical counterpart HDE 226 868. These events appear to be the same as previously reported absorption dips and reveal this phenomenon to be more complex than had been believed. A systematic study of the X-ray spectral variations in these energy bands, on a time scale of 64 seconds over the period of the spectroscopic binary, is presented.Paper presented at the COSPAR Symposium on Fast Transients in X-and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.On leave from Institute of Space and Aeronautical Science, University of Tokyo. |
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